Alfred Hitchcock's magnum opus, North by Northwest, may not be based on a true story, but it does have some real-life inspirations. Often touted as one of the greatest movies of all time, North by Northwest focuses on Roger O. Thornhill (Cary Grant), who gets embroiled in a web of peril and espionage when a group of spies mistakes him for a government agent named George Kaplan. With what follows, Roger finds himself embarking on a thrilling journey across the country to uncover the mysteries behind the name and prove his innocence to his pursuers.

https://screenrant.com/north-by-northwests-true-story-inspiration-explained/